Sir - I am writing about medical research on animals.

My border collie Megan had a stroke which left her conscious but partially paralysed on her left side. As a doctor, I was interested to compare her reactions to the ones people usually show (and mine as fond owner).

At first, she stumbled around in tight circles and often collapsed. However, her expression was of perplexity, as when she has failed to see where her ball has landed. She did not seem anxious or afraid and her heart rate did not go up.

After a sleep, she discovered she could get round the house without falling, provided she chose a route where there was something to lean against on her left.

Soon she struggled to bring a bone for me to throw. She ate as usual that evening. Now she has almost recovered. All this makes me think that producing a brain lesion in a painless way in an animal to simulate, for example, Parkinson's disease for research purposes, does not cause the anguish that the equivalent would in a person.

Megan shows anxiety and fear clearly, but obviously did not feel threatened by what had happened to her. I was the one who was distressed and worried, wondering whether she was about to die or would have to be put down, and how I would cope with a paralysed dog.

Those who protest against using animals for research should not assume that they have the same emotional reactions to injury and disease that we do. Provided they are given good care, they may be as free from suffering as Megan was.

Avril Stedeford

(Retired psychiatrist)

Sandfield Road

Headington

Oxford